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Date: Mon, 23 Aug 2010 13:48:20 -0700
From: Yinghai Lu <yinghai@...nel.org>
To: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Len Brown <len.brown@...el.com>,
Suresh Siddha <suresh.b.siddha@...el.com>
CC: linux-kernel@...r.kernel.org
Subject: [PATCH] x86: Disabling x2apic if nox2apic is specified
for
1. x2apic preenabled system
2. first kernel have x2apic enabled, and try to boot second kernel with "nox2apic"
Signed-off-by: Yinghai Lu <yinghai@...nel.org>
---
arch/x86/include/asm/apic.h | 6 ++++
arch/x86/include/asm/apicdef.h | 1
arch/x86/kernel/acpi/boot.c | 10 ++++++-
arch/x86/kernel/apic/apic.c | 54 ++++++++++++++++++++++++++++++++---------
arch/x86/mm/srat_64.c | 12 ++++++++-
5 files changed, 69 insertions(+), 14 deletions(-)
Index: linux-2.6/arch/x86/include/asm/apic.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/apic.h
+++ linux-2.6/arch/x86/include/asm/apic.h
@@ -176,6 +176,7 @@ static inline u64 native_x2apic_icr_read
}
extern int x2apic_phys;
+extern int nox2apic;
extern void check_x2apic(void);
extern void enable_x2apic(void);
extern void x2apic_icr_write(u32 low, u32 id);
@@ -186,6 +187,10 @@ static inline int x2apic_enabled(void)
if (!cpu_has_x2apic)
return 0;
+ /* avoid to read msr */
+ if (nox2apic)
+ return 0;
+
rdmsr(MSR_IA32_APICBASE, msr, msr2);
if (msr & X2APIC_ENABLE)
return 1;
@@ -214,6 +219,7 @@ static inline void x2apic_force_phys(voi
#define x2apic_preenabled 0
#define x2apic_supported() 0
+#define nox2apic 1
#endif
extern void enable_IR_x2apic(void);
Index: linux-2.6/arch/x86/kernel/acpi/boot.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/acpi/boot.c
+++ linux-2.6/arch/x86/kernel/acpi/boot.c
@@ -213,6 +213,8 @@ static int __init
acpi_parse_x2apic(struct acpi_subtable_header *header, const unsigned long end)
{
struct acpi_madt_local_x2apic *processor = NULL;
+ int apic_id;
+ u8 enabled;
processor = (struct acpi_madt_local_x2apic *)header;
@@ -221,6 +223,8 @@ acpi_parse_x2apic(struct acpi_subtable_h
acpi_table_print_madt_entry(header);
+ apic_id = processor->local_apic_id;
+ enabled = processor->lapic_flags & ACPI_MADT_ENABLED;
#ifdef CONFIG_X86_X2APIC
/*
* We need to register disabled CPU as well to permit
@@ -229,8 +233,10 @@ acpi_parse_x2apic(struct acpi_subtable_h
* to not preallocating memory for all NR_CPUS
* when we use CPU hotplug.
*/
- acpi_register_lapic(processor->local_apic_id, /* APIC ID */
- processor->lapic_flags & ACPI_MADT_ENABLED);
+ if (nox2apic && (apic_id >= 0xff) && enabled)
+ printk(KERN_WARNING PREFIX "x2apic entry ignored\n");
+ else
+ acpi_register_lapic(apic_id, enabled);
#else
printk(KERN_WARNING PREFIX "x2apic entry ignored\n");
#endif
Index: linux-2.6/arch/x86/kernel/apic/apic.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/apic/apic.c
+++ linux-2.6/arch/x86/kernel/apic/apic.c
@@ -137,15 +137,14 @@ int x2apic_mode;
#ifdef CONFIG_X86_X2APIC
/* x2apic enabled before OS handover */
static int x2apic_preenabled;
+int nox2apic;
static __init int setup_nox2apic(char *str)
{
- if (x2apic_enabled()) {
- pr_warning("Bios already enabled x2apic, "
- "can't enforce nox2apic");
- return 0;
- }
+ if (x2apic_enabled())
+ pr_warning("Bios already enabled x2apic, will disable it");
+
+ nox2apic = 1;
- setup_clear_cpu_cap(X86_FEATURE_X2APIC);
return 0;
}
early_param("nox2apic", setup_nox2apic);
@@ -1343,8 +1342,33 @@ void __cpuinit end_local_APIC_setup(void
}
#ifdef CONFIG_X86_X2APIC
+
+static void disable_x2apic(void)
+{
+ int msr, msr2;
+
+ if (!cpu_has_x2apic)
+ return;
+
+ rdmsr(MSR_IA32_APICBASE, msr, msr2);
+ if (msr & X2APIC_ENABLE) {
+ pr_info("Disabling x2apic\n");
+ /*
+ * Need to disable xapic and x2apic at the same time at first
+ * then enable xapic
+ */
+ wrmsr(MSR_IA32_APICBASE, msr & ~(X2APIC_ENABLE | XAPIC_ENABLE),
+ 0);
+ wrmsr(MSR_IA32_APICBASE, msr & ~X2APIC_ENABLE, 0);
+ }
+}
void check_x2apic(void)
{
+ if (nox2apic) {
+ disable_x2apic();
+ return;
+ }
+
if (x2apic_enabled()) {
pr_info("x2apic enabled by BIOS, switching to x2apic ops\n");
x2apic_preenabled = x2apic_mode = 1;
@@ -1355,6 +1379,11 @@ void enable_x2apic(void)
{
int msr, msr2;
+ if (nox2apic) {
+ disable_x2apic();
+ return;
+ }
+
if (!x2apic_mode)
return;
@@ -1380,7 +1409,7 @@ int __init enable_IR(void)
return 0;
}
- if (enable_intr_remapping(x2apic_supported()))
+ if (enable_intr_remapping(x2apic_supported() && !nox2apic))
return 0;
pr_info("Enabled Interrupt-remapping\n");
@@ -1399,7 +1428,7 @@ void __init enable_IR_x2apic(void)
int dmar_table_init_ret;
dmar_table_init_ret = dmar_table_init();
- if (dmar_table_init_ret && !x2apic_supported())
+ if (dmar_table_init_ret && (!x2apic_supported() || nox2apic))
return;
ioapic_entries = alloc_ioapic_entries();
@@ -1423,12 +1452,15 @@ void __init enable_IR_x2apic(void)
else
ret = enable_IR();
+ if (nox2apic)
+ goto without_x2apic;
+
if (!ret) {
/* IR is required if there is APIC ID > 255 even when running
* under KVM
*/
if (max_physical_apicid > 255 || !kvm_para_available())
- goto nox2apic;
+ goto without_x2apic;
/*
* without IR all CPUs can be addressed by IOAPIC/MSI
* only in physical mode
@@ -1444,7 +1476,7 @@ void __init enable_IR_x2apic(void)
pr_info("Enabled x2apic\n");
}
-nox2apic:
+without_x2apic:
if (!ret) /* IR enabling failed */
restore_IO_APIC_setup(ioapic_entries);
legacy_pic->restore_mask();
@@ -1459,7 +1491,7 @@ out:
if (x2apic_preenabled)
panic("x2apic: enabled by BIOS but kernel init failed.");
- else if (cpu_has_x2apic)
+ else if (cpu_has_x2apic && !nox2apic)
pr_info("Not enabling x2apic, Intr-remapping init failed.\n");
}
Index: linux-2.6/arch/x86/mm/srat_64.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/srat_64.c
+++ linux-2.6/arch/x86/mm/srat_64.c
@@ -125,6 +125,13 @@ acpi_numa_x2apic_affinity_init(struct ac
if ((pa->flags & ACPI_SRAT_CPU_ENABLED) == 0)
return;
pxm = pa->proximity_domain;
+ apic_id = pa->apic_id;
+#ifdef CONFIG_X86_X2APIC
+ if (nox2apic && (apic_id >= 0xff)) {
+ printk(KERN_INFO "SRAT: PXM %u -> X2APIC 0x%04x ignored\n",
+ pxm, apic_id);
+ return;
+ }
node = setup_node(pxm);
if (node < 0) {
printk(KERN_ERR "SRAT: Too many proximity domains %x\n", pxm);
@@ -132,12 +139,15 @@ acpi_numa_x2apic_affinity_init(struct ac
return;
}
- apic_id = pa->apic_id;
apicid_to_node[apic_id] = node;
node_set(node, cpu_nodes_parsed);
acpi_numa = 1;
printk(KERN_INFO "SRAT: PXM %u -> APIC 0x%04x -> Node %u\n",
pxm, apic_id, node);
+#else
+ printk(KERN_INFO "SRAT: PXM %u -> X2APIC 0x%04x ignored\n",
+ pxm, apic_id);
+#endif
}
/* Callback for Proximity Domain -> LAPIC mapping */
Index: linux-2.6/arch/x86/include/asm/apicdef.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/apicdef.h
+++ linux-2.6/arch/x86/include/asm/apicdef.h
@@ -140,6 +140,7 @@
#define APIC_BASE (fix_to_virt(FIX_APIC_BASE))
#define APIC_BASE_MSR 0x800
+#define XAPIC_ENABLE (1UL << 11)
#define X2APIC_ENABLE (1UL << 10)
#ifdef CONFIG_X86_32
--
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